Reversing line starter interlock



May 23, 1944.

D. ELLIS ET AL REVERSING LINE STARTER INTERLOCK Filed Feb. 18, 1942 d R mwm L N l- N $e R wmw m I a T EC A f 8 CM dB f 6M D QV E 4 w E in Y 4 F w A Nd av WITNESSES:

Patented May 23, 1944 UNITED STATES PATENT OFFICE REVERSING LINE STARTER 'INTERLOCK Application February 18, 1942, Serial No. 431,400

4 Claims.

The present invention relates to a reversin line starter interlock, and more particularly, to an improved arrangement of parts for controlling the connections to an electric motor for forward and reverse drive.

One of the principal objects of this invention isto'providein a'circuit controller'having-a pair of independently operable-switches, an improved arrangement of parts'interlocking the operation of the switches by which simultaneous electrical.

in a control of the character referred to an interlock for a pair of switches comprising a pair of pivotally mounted levers respectively having a connection with one of the switches and interengageable parts by which movement of one of the switches toward closed position will be effective to move the other of the switches to open position.

A further object oithis invention is to provide in an interlock for moving one switch to open position upon movement of another switch to closed position, an arrangement of parts by which simultaneous movement of the switches in unequal increments willbe had.

A further object of the invention is to provide an interlock for effecting simultaneous movement of a pair of switches to different positions by unequal increments in which 'a given 'unit of movementof one switch towardclosed position will'beeffective toimpart a larger unit of movement to the other switch for moving such other switch from its closed position to its open position.

Other objects and'advantages of this invention will become'apparent from a study of the following description and accompanying drawing, in which:

Figure l is an elevational view, parts thereof being shown in section, of an interlock constructed in accordance with the principles of this invention, and showing the manner in which the interlock is arranged between a pair of switches;

Fig. 2 is a broken away viewof the interlocks;

shown in Fig. 1, showing the relative position between the parts of the interlock at one point during operation of the same to move one of the switches from its closed to its open position;

Fig. 3 is a view similar to Fig. 2 showing the position of the parts of the interlock after operation to reverse the connections providedby the switches in Fig. 1; and

Fig. 4 is a view similar to Fig. 2, with the interlocking levers omitted.

Referring to the drawing, the numeral 5 designates as a whole, a circuit control unit comprising a plate 6 having mounted thereon a pair of switches I and 8. The switches I and '8, respectively, are provided with a set of stationary contacts 9 and I0 and a set of movable contacts H and I2; The movable contacts H and I2; respectively,.are carried by actuating members [3 and I4 which are movable up and down, as viewed in Fig. 1, with respect to the plate 6 for opening and closing the switches l and 8. The actuators I3 and M are, respectively, connected to the armatures I5and I6 of electromagnets I1 and I8. Upon energization of either the electromagnet I! or the electromagnet t8, the switches l or 8 will be closed, according to the electromagnet selected, in a manner well known in the art.

The switches l and 8 are particularly adapted for reversing the connections of an electric motor acrossa line energized by a suitable source of power for controlling the forward and reverse drive of the motor. However, since the abovedescribed parts per se form no part of this invention, it will be understood that the novel features of this invention withrespect to the interlock intermediate the switches 1 and 8 are applicable to other types of bust transfers wherein it is desired to change theline connections of an electric load.

The interlock for the switches and 8 is indicated as a whole by the numeral I9 and comprises a plate 20 mounted on the support 6, the plate 20 being an auxiliary support having a bracket 2| projecting therefrom. Interlocking levers 22 and 23 are, respectively, provided for cooperation with the switches I and 8. Each of the levers 22 and 23 is provided with a pivot 24 intermediate the ends thereof connecting the same to the bracket 2|, the pivots 24 being spaced from each other and lying intermediate the switches 1 and 8. The levers 22 and 23 are in the nature of bell crank levers, respectively, having outwardly projecting arms 25 and 26 and inwardly projecting arms 21 and 28. The arm 25 of the lever 22 operatively engages member I3 and the arm 26 of lever 23 operatively engages member IG, as shown. The said connections of the ends 23 and 33 with the switch actuating members I3 and I4 are such that the arms 25 and 26 will be pivoted about their respective pivots 24 in accordance with movement imparted to the actuating members I3 and I4. The arm 27 of the lever 22 is provided with a roller 3! at the outer end thereof for engagement with-a cam 32 formed on the outer end of the lever 28. The cam 32 is provided with two'surfaces33 and 34 which cooperate with the-roller 3| in transmitting movement between the levers 22 and 23 in unequal increments ina manner to be described.

The operation of the interlock is as follows:

Upon energization of the magnet I8, the armature I3 and member I4 will be moved upwardly as viewed in Fig. 1, to close the contacts l3 and I2. 'Upward movement of the member I4 will move the lever 23 in a counterclockwise direction. counterclockwise movement of the lever 23 will cause the arm 28 thereof to move to the left and down, as viewed in Fig. l, and the camming surface 34 will be effective to cam the roller 3| to the left andmove the lever 22 about its pivot 24 in a counterclockwise direction. Upon movement of the lever 22 in a counterclockwise direction, the end 29 of the arm 25 will move member I3 downwardly to thus move the contacts II out of engagement with the sta open position, as shown, to their closed position. The movement of the levers 23 and 22 in unequal increments is effective upon an initial small unit of movement of the actuator I4 and contacts I2 toward closed position to move the member I3 and contacts II to their substantially fullopen position. The movement of the switches 'I and 8 in this manner provides a very desirable feature in that it prevents the connection of the load to the source of power through both the switches I time. In controls employing switches of the type illustrated, it is necessary to conserve space and it is desirable that the extent of relative movement permitted between the contacts II] and I2 be kept as small as possible. Due to the. fact that the movable contacts II and I2 in such switches are usually spring biased for movement relative to their support, it will be apparent that the effective space or gap between the contacts I U and I2 is further decreased. The decrease in effective space between the stationary and movable contacts is due to the fact that as the support for the movable contacts is actuated to open the circuit, the spring bias (not shown) is and 8 at the same effective to maintain the contactors in closed position during a, portion of the movement of the actuation or support away from closed position. In interlocksheretofore available which operate to impart equal movement to both sets of movable contactors, the contactors moving to closed position are practically in such position at about the same time that the other contors such as arcing or improper adjustment, the undesirable feature of the circuit being closed, at least momentarily through both switches, has frequently presented itself. By imparting movement to the switches 1 and 8 in unequal increments, the interlock of this invention successfully preventsthe disadvantage referred to.

The manner in which the interlocking levers 22 and 23 operate to impart movement to the switches 1 and 8 in unequal increments will be best understood by referring to Figs. 1, 2 and 3, which show the different positions which the levers 22 and 23 pass through as the switch 8 moves from open to closed position, and as the switch 7 moves from its closed to open position. in Fig. l, the switch 8 is in its full open position and the switch 'I is in its full closed position. In the showing of Fig. 1, it will be noted that the roller 3| on the lever 22 is in engagement with the camming surface 34 on the lever 23. vAs soon as the magnet I8 is operatecL'the armature IE will be actuatedto draw the member I4 upwardly. as viewed in Fig. 1. During 'a relatively small initial upward ,movement of ,the member I4, the interlocking levers 22 and 23 will be moved to the position shown in Fig. 2, in which position the actuating member I4 will have moved slightly from the position shown in Fig. 1 and the actuating member I3 will have moved into the same position as occupied/by the actuating member I4 after a small initial movement, and in this position both setsof movable contacts II and I2 will be in their substantially full .open position with no danger of completion of the circuit to the electric load through either of the switches l or 8. In otherwords, a small initial movement of the actuating member I4 to move the switch 8 toward closed position is effective to impart a relatively greater movement to the actuating member I3 and thereby movement of the switch 'I to its substantially full open position. The unequal increment of movement transmitted from the lever 23 to the lever 22 is due to the fact that, as pivotal movement of the lever 23 is started, the camming surface 34 is arranged substantially tangential to the movement of its point of contact with the roller 36. Accordingly, as the camming surface 34 moves to the left,'to the position shown'in Fig.

2, the roller 3I, and thereby the lever; 22, will of the lever 23 will be had upon movement of the tactors are leaving closed position. Due to facswitch 8 to its fully closed position, and the levers 22 and 23 will be moved to the position shown in Fig. 3. However, during this continued movement, the point of contact of the roller 3I with the lever 23 will move from the camming surface 34 onto the camming surface 33. As the roller 3I moves onto the camming surface .33, continued movement of the lever 23 will cease to be effective to impart greater movements to the lever 22 and a reverse "action-will be had. In other words, as the lever 23 moves H from the position shown in Fig. 2 to the position shown in Fig. 3, arelatively small amount of 'movement will be .imparted to the lever 22.

Since it will be recalled that when the levers 22 and 23 are in the-position :shown in'Fig. '2,' the switch "I is in the substantially open position, and it will be apparent that a large movement of thelever 22 is, therefore, not necessary in order to open the switch I.

With the levers 2-2 and 23 in the position shown "in-Fig. 3, the switch I Will be in its open position and the switch 8 will be in its closed position.

Thereafter, upon energization of theelectromagnet I! to close the switch I, the levers 22 and 23 will be moved consecutively from the position shown in 3 through the position shown in Fig. 2-and into the position shown-in Fig. 1. In this sequence of movements, the roller 3| will be effective to actuate the lever 23 in the same manner that the lever 22 is actuated by the camming surfaces 3d and 33 in the sequence of movements described above.

It will be noted that when either-of'the switches land 6 is in closed position, one of the camming surfaces 33 and 35 will be in engagement with the roller 35 Upon subsequent operation to close one of the switches, the roller 3! will move out of engagement with such camming surfaces into engagement with the other camming surface. It is during the movement of the roller 3| out of engagement with'one of the camming surfaces 33 and 34 that the switch in closed position is moved to its open position. As pointed out above, the movement imparted to the switch being opened is much greater than that initially imparted to the switch being closed and this movement of the switches in unequal increments takes place during movement of one of the camming surfaces 53 or 34 out of engagement with the roller 3i. Subsequent movement of the roller 3! into engagement with the other of the camming surfaces 33 or 34 is eifective to impart comparatively little further movement to the switch moving to open position. During such subsequent movement, most of the movement of the switch being closed takes place. In this manner the gap between the contacts necessary for arc extinguishment is maintained at a maximum.

It is also to be noted that the particular arrangement of the levers 22 and 23 with respect to the armatures l and i6 is effective to maintain lost motion at a minimum. The axes of the pivots 2d are perpendicular to the plane in which rectilinear movement of the armatures l5 and It takes place. Lost motion can thus occur only at the lever armature connections 29 and 3D and at the lever ends 3! and 32. There is thus provided a minimum of relatively movable parts in the interlock between the switches l' and 8.

To adjust the positions of the levers 22 and 23 relative to each other, and the actuating members Hi and l3, the auxiliary supporting plate 2t is provided with elongated slots 35 in alignment with threaded openings 36 formed in the main supporting plate 6. Setscrews 31 adapted to have engagement in the threaded openings 36 are provided for securing the plate 29 in a given position of adjustment. In order to guide the plate along a center line midway between the pivots 24, there are provided slots 38 and 39 through which project members 40 and 4| lanced out of the surface of the plate The projecting members 4i) and ti respectively engage with the parallel sides of the slots 38 and 39 and will guide the plate 29 along the vertical center line parallel to the edges of the slots 38 and 39. In order to adjust the position of the plate 20, it is merely necessary to loosen the setscrews 3i and slide the plate 2:2 up or down, as viewed in Fig. 1, with respect to the plate 5. Such movement will effect pivotal movement or" the levers 22 and 23 about their pivots 24 and thereby adjust the clearance between the rollers 3| and 32 and the positions of the ends 29 and '30 with respect to the actuating parts I3 and I4. I

Since certain changes may be made in the above described construction and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter contained in'the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. In an electric circuit controller, a support, a pair of switches mounted on said support and movable between open and closed positions, and coupling means interconnecting said switches for moving one of said switches to open position uponmovement of the other of said switches to closed position, said means comprising a pair of bell cranks pivotally mounted on said support, each of said bell cranks having an arm connected to one of said switches for movement therewith, and a motion transmitting arm, said motion transmitting arms having cooperating camming parts eifective upon a small initial movement of one of said bell cranks and its associated switch toward closed position to cam the other of said bell cranks and its associated switch to its substantially full open position, the cam part of one of said arms having a cam curve pointed towards said other cam part, and said coupling means being arranged relative to said switches so that the point of engagement between said cam parts passes through the point of said cam curve substantially at the moment when the closed switch is opened.

2. In an electric circuit controller, a support, a pair of switches mounted on said support and movable between open and closed positions, and means interconnecting said switches for moving one of said switches to open position upon movement of the other of said switches to closed position comprising a pair of levers respectively mounted for pivotal movement on said support about points intermediate the ends thereof, each of said levers having one of its ends connected to one of said switches for movement therewith, the other ends of said levers respectively having a roller and a camming member, said member having a pair of camming surfaces engageable with said roller and forming an intermediate cam point directed towards said roller, one of said camming surfaces and said roller being effective upon a small initial movement of one of said levers and its associated switch toward closed position to cam the other of said levers and its associated switch to substantially full open position when the point of engagement of said roller with said camming member passes through said cam point.

3. In an electric circuit controller, a support, a pair of switches mounted on said support and movable between open and closed positions, each of said switches having an actuating member recthe point of engagement between said cam parts passes through the point of said cam ,curve substantially at the movement when the closed switchis opened;

A. In an electric circuit controller, a support,

a pair of switches mounted on said support and movable between open and closed positions, each of, said switches having an actuating memberrectilinearly movable in parallel to the movement of a the other member, and coupling means interconnecting said members for moving one of said switches to open position upon movement of the other of said switches to closed position, said means comprising a base and a pair of levers mounted on said base for pivotal movement withina plane in parallel to the movement of said ;actuating members, each of said'levers having one of its ends engaged with on; O said actuating members so that it pivots in response to rectilinear movement of such member, the other ,ends of said levers respectively having a roller and camming member, said camming member having a pair of angularly related camming surfaces engaged with said roller, one of said camming surfaces and said roller being efiective upon a small initial movement of one of said levers and its associated switch actuating member toward closed position to cam the other of said levers and its associated switch to substantially full open position, the other of said camming surfaces and said roller cooperating to provide a similar camming action for said one lever upon subsequent movement of said other lever and its associated switch actuating member toward closed position, and said base being adjustably mounted on said support so as to be slippable along a plane in parallel to said first mentioned plane in order to adjust said pair of levers relative to said actuating members.

DELBERT ELLIS.

BRUCE C. WELLS. 

